/**
 * Globally disable all animations
 * This may be desirable for used on a low-resource device.
 */ 
$.fx.off = true;

/**
 * Display or hide the matched elements.
 */
<script>
  $(document).ready(function() {
    $('.btn').click(function() {
      $(".target-container").toggle("slow");
    });
  });
</script>